Hmmm. The aim offset looks good to me. I guess the next thing I would try would be to hook the output of your State Machine directly to the Final Pose of your AnimGraph and just bypass everything else. If it still looks broken, I would probably make a new AnimBP from your skeleton and then check your assets in there a piece or two at a time. For example, you could just plug your Idle animation into the Final Pose of your test AnimBP and see if that plays correctly. Then you could add your Aim Offset to that Idle, etc and see where it breaks down.
Hope that helps!